1. Field of the Invention
Artificially inducing ballistic dispersion into high firing-rate guns can be traced back to the period immediately following the American Civil War, at least insofar as the development of techniques and patented mechanisms for accomplishing such.
2. Prior Art
These efforts were directed solely to multibarrel gun applications, and are shown, for example in the following patents: U.S. Pat. No. 137,428, Farwell, Apr. 1, 1873; U.S. Pat. No. 145,563, Gatling, Dec. 16, 1873; U.S. Pat. No. 154,596, Farwell, Sept. 1, 1874; U.S. Pat. No. 173,751, Bailey, Feb. 22, 1876; U.S. Pat. No. 173,752, Bailey, Feb. 22, 1876; U.S. Pat. No. 179,450, Farrington, July 4, 1876; U.S. Pat. No. 182,729, Wilder, Sept. 26, 1876; U.S. Pat. No. 198,367, Farrington, Dec. 18, 1877; U.S. Pat. No. 211,737, Hotchkiss, Jan. 28, 1879; U.S. Pat. No. 211,849, Hotchkiss, Feb. 4, 1879; U.S. Pat. No. 218,190, Palmcrantz, Aug. 5, 1879; U.S. Pat. No. 220,545, Palmcrantz; Oct. 14, 1879; U.S. Pat. No. 298,493, Nordenfelt, May 13, 1884; U.S. Pat. No. 340,725, Nordenfelt, Apr. 27, 1886; U.S. Pat. No. 563,701, Wilder, July 7, 1896. An attendant logic for controlling these mechanisms in practice was not developed and field test data were not obtained to support the claims made. Emphasis was placed on the development of mechanisms for spreading or scattering shots traversely a prescribed distance apart. No attempt was made based on the expected engagement conditions to control the size, shape, and density of the ballistic pattern being built up at the target. These parameters inter alia collectively influence whether or not hits are obtained on target and, more importantly, that it is damaged to some acceptable state. While mechanisms patented since World War I, again for application to high firing-rate multibarrel guns, address the problem of increasing or decreasing the induced ballistic dispersion either to a preset value or continuously adjusted while firing, they again collectively and individually make no attempt to define a control logic for deploying the system effectively, and are shown, for example, in the following patents: U.S. Pat. No. 1,334,983, Arter, Mar. 30, 1920; U.S. Pat. No. 1,353,267, Pierce, Sept. 21, 1920; U.S. Pat. No. 1,448,587, Arntzen, Mar. 13, 1923; U.S. Pat. No. 1,551,809, Dodge, Sept. 1, 1925; U.K. Pat. No. 705,568, North et al, Mar. 17, 1954; U.S. Pat. No. 3,380,343, Chiabrandy and Tassie, Apr. 30, 1968; U.S. Pat. No. 3,897,714, Perrin, Tassie, and Smith, Aug. 5, 1975.
Supporting theoretical and essentially analytical investigations of the worth of induced dispersion for enhancing weapon system effectiveness were not to follow until the period between the two World Wars. These efforts were, for the most part, largely focused on pattern bombing, i.e., the deliberate spacing of free-fall bombs by prescribed spacing of aircraft in formation, salvo (scatter) bombing, or train (stick) bombing in order to insure that (1) the target is straddled by the bomb pattern released, and (2) the pattern density is such that no less than a specified number of bombs impact in the target area. It was not until the late 1930's and earlier 1940's that investigations of the worth of gunnery dispersion on its own merits were seriously undertaken here and abroad, and these have continued sporadically since World War II. These efforts too have been largely theoretical in nature and, thus, until now a viable dispersion-controlled gunnery system has remained essentially a will-of-the-wisp.
The basic problem facing these earlier investigators was their inability to satisfactorily map, measure, and describe analytically the gunnery process with the analytical tools and instrumentation then available. For high firing-rate guns, either with single or multiple barrels, the ballistic pattern is defined by a rapid and continuous sequence of projectiles directed at the target. The projectiles do not generally follow each other in exactly the same path, and, as a consequence, a dispersed pattern is built up at the target. The statistical characteristics of the resulting pattern generally involve three aspects. First, given target detection and assignment, there is the process involving certain random elements of bringing the gun to bear on target and keeping it on target during the engagement. From this process the requisite gun orders are generated. Because the errors in tracking are both auto-correlated and cross-correlated, so too are the gun orders generated. Superimposed on the tracking and gun-order generation process is the second aspect, viz., the ballistic dispersion. This process also involves several random elements, but in a different manner from the first aspect, since this random dispersion varies independently projectile to projectile, i.e., it is uncorrelated. Since this aspect is superimposed on the first, the tracking and gun-order auto-correlation and cross-correlation are induced on the sequentially ordered projectiles as they are fired. The third aspect arises because many of the engagement parameters--individual projectile hit probabilities, target vulnerability, auto- and cross-correlations, projectile time-of-flight, etc.--can and do change markedly during the firing interval. These essentially Lexian effects must be accounted for since they can change at a rate equal to the cyclic rate of fire of the gun. While these observations have all been confirmed by extensive field test programs conducted by both contractors and military and naval services here and abroad since World War II, no attempt has been made to develop a model for combining these separate but interrelated aspects of the gunnery process into a logical treatment of the whole.